I looked for a hobby/model shop out near Dulles (actually, the Chantilly area) a few years back when I visited the area, I couldn't find said shop... I don't remember the name of the shop, sorry.
You'd think that with so much military stationed around the WashDC area, the airports between Baltimore and Dulles and with all of the high-tech job fields that there would be more model shops up there, but NO.